As a means for providing the indications of scale, etc. on fluororesin-coated materials, there are conventionally only means which utilize the shadow of recesses and protrusions physically formed by pressing the coated materials, that is, only means using press-markings.
This is because fluororesins are non-tacky and hence indications such as scale, etc. are difficult to be provided on the surfaces thereof by printing. Even if printing could be made, the non-tacky property of the printed parts would be lowered. Accordingly, when they are used in the field of kitchen utensils such as inner pots of rice cookers, undesirable phenomenon occurs in that rice sticks onto the printed parts.
For this reason, indications on kitchen utensils such as pots of rice cookers have been entirely made by press-markings. However, these means have serious problems.
Firstly, the press-marked parts of coated materials are deformed by a very high curvature and fluororesin coatings are thus stretched so that the coatings are liable to be peeled off from the substrate at the interfaces, and/or pinholes, cracking, etc. are apt to be formed on the coatings and there is a possibility that water and boiled rice soup penetrate through the pinholes or cracks and the corrosion of substrates, the peeling of the coatings, discoloration, etc. are caused. Secondly, indications are hard to see since the indications are provided by shadow made by recesses and protrusions.
Rice cookers have been intended to have multi-functions in recent years. Accordingly, on the inner pots of the rice cookers, not only a kind of marking for rice cooking but also many kinds of markings for rice to be boiled with red beans, rice gruel, glutinous rice, etc., for example, three or four kinds of markings have been required, and the number of markings has been increased so that the above-described problems have been actualized.